Apparatus for producing sheet metal by electrodeposition



Dec. 23, 1958 J. ZOLDAS APPARATUS FOR PRODUCING SHEET METAL BY ELECTRODEPOSITION Filed May 14, 1956 INVENTOR BY John Zoldos ATTORNEYS tates APPARATUS FOR PRGDUCING Sl'tEET METAL BY ELECTRODEPOSHIGN John Zoldas, Perth Amboy, N. 3., assigror to The Anacontla Company, New York, N. Y., a corporation of Montana Application May 14, 1956, Serial No. 584,716

Claims. (Cl. 204-208) improved surface quality and of improved uniformity 'of gage'across the Width of the cathode drum on which it is formed. The invention also provides improvements in theapparatus used for producing electrodeposited sheet metal in accordance with the new method.

Numerous proposals have been made heretofore for producing a variety of metals in .sheet form by electrodeposition on a rotating drum cathode, and sheet copper has been thus producedon a commercial scale for many years. The electrodeposition'method has the advantage that 'sheetsof wide width, thin gage, .and indefinitely long lengths can be produced. Sheet metal made in this manner, however, is subject to considerable variation in 'thickness across thewidth of the sheet; .and it is difficult to produce metalof very thin gage (weighing, say, one

ounce or'less per square foot, .in the case of copper) that'is free frompinholes. Heretofore the only .way by which it has been possible to produce electrodeposited sheet copper having sufiicient uniformity of gage and freedom from pinholes, in thicknesses corresponding to "weights of one ounce to two ounces per'square foot,'has been to subject the electrolyte between the cathode drum and the nearby anode to intense air agitation.

While air agitation has been necessary to produce electrodeposited sheet copper of acceptable quality, such agitation is .by no means free from objection. It causes .muchsplashing of the electrolyte, with the result that the atmosphere in the vicinity of the electrodeposition equipment becomes charged with an irritating acid mist. 'Workmen in the areamust wear some form of respiratory protective apparatus, and the acid mist promotes discolorationand even damaging corrosion to the electrodeposited sheet. Splashing and sloshingof the electrolyte .near the cathode drum also results in wetting and trap- ,pingof specks of lead dust (generated by the cathode polishing-apparatus) on the surface of the cathode drum, leading to a defect in the deposited sheet metal known as leaded porosity. And of course the splashing of electrolyte and the. acid. mistin the vicinity of theelectrodeposition equipmentpromotes rapid corrosion of the apparatus.

v Inaccordancewith the method of this-invention'it is possible to eliminate air agitation of the electrolyte, and .all its attendingdisadvantages, and at the same time to produce electrodeposited sheet metal of notably better uniformity of gage thickness than can be produced with air agitation, by forcibly projecting a turbulent stream of electrolyte into the space between the cathode drum and; the adjacent anode, across substantially the entire width of the drum. The stream of electrolyte overflows from the space between cathode and anode without 2,865,830 Fatented Dec. 2 3, 1958 splashing or producing any mist of acid electrolyte droplets. Yet a cathode deposit of remarkable uniformity is produced, which when stripped from the cathode drum forms a sheet of notable uniformity of gage across its width and freedom from objectionable pinholes and other defects.

Preferably the stream of electrolyte is'delivered substantially continuously into the space between the cathode drum and the. anode, and is introduced into that space adjacent the line of deepest immersion of the cathode drum in the electrolyte( The stream then is projected upwardly in turbulent flow along the surface of each of the two lower quadrants of the drum. Preferably the stream of electrolyte flowing turbulently through the space between cathode drum and anode is maintained substantially free of gas bubbles (especially air or other gas purposely introduced) in order to eliminate to the greatest possible extent the risk of introducing any acid mist into the atmosphere. However, a small amount of air or other gas may be utilized to promote agitation of the electrolyte without sacrificing altogether the improved quality of the electrodeposited sheet that is attained in accordance with the invention.

The apparatus of the invention comprises a cathode drum mounted for -rotation on a horizontal a i a cylindrically curved anode -r noun ted in closely spaced relation with the cathode drum, and means for projecting .a turbulent fiowofelectrolyte into the space between anode and cathode. These means comprise a discharge manifold which extends along an edge of the anode. The discharge manifold comprises an elongated tubular member divided longitudinally into a distribution compartment and a discharge compartmentcommunicating therewith. Means are provided for delivering electrolyte solution into the distribution compartment, and the vdischarge compartment vis provided with a series of spaced solution outlets along substantially the entire length of the discharge manifold. Thus a stream of electrolyte delivered under pressure into said distribution compartment is projected substantially uniformly through said outlets into the spacebetween anode and cathode.

Generally the apparatus comprises a pair of cylindrically curved anodes each mounted in closely spaced relation with one of the lower quadrants of the cathode drum, and with the adjacent edges of the anodes spaced apart substantially along the lowermost portion ofthe cathode drum. In such apparatus the discharge manifold is preferably positioned between the spaced adjacent edges of the anodes.

A preferred embodiment of the method andapparatus ofthe invention is described below with reference to the aocompanyingdrawings. While the invention is applicable generally to all metals that'can be electrodeposited in sheet form-both the new method and the new apparatus-are especially suitable for use in conjunction with the production of sheet copper by .electrodeposition from anacidic aqueous copper-bearing electrolyte. Accordingly; the following-description refers particularly to the 60 production of electrodeposited sheet copper. In the drawings,

Fig.1 is a11 elevation, partly in section, through ap- [paratus for producing sheet copperby electrodeposition on a rotating drum cathode;

Pig. 2 is an elevation, partly in section and .on an enlarged scale, of the discharge manifold by which electrolyte is projected'forcibly into the space between anode and cathode in the apparatus shown in Fig. 1; and

Fig; 3 isa cross section through thedischarge mani- V fold taken substantially along the line-33 of Fig-2.

The apparatus shown in Fig. 1 comprises a tank 10 of 'concrete or other material which is'provided interiorly with a lining 11 of lead and is supported on piers 12. An electrolyte inlet conduit 13 provides for introducing v electrolyte intermittently or continuously, as desired, into the tank, and an electrolyte outlet conduit 14 receivesthe overflow of electrolyte from the tank and provides for maintaining a desired level 'of electrolyte in the tank. A valved drain pipe 15 is provided for emptying the tank whenever necessary. 7

A cylindrical cathode an axial shaft 17 which extends through bearings 18 mounted on the sides of'the tank. 10. The drum is slowly rotated in the direction indicated by the'arrows by means of a sprocket chain 19 engaging sprocket wheels 20 and 21 mounted respectively on the drum shaft 17 and on a drive shaft 22. The drive shaft is continuously rotated by a motor (not shown).

The cathode drum 16 extends about half into and half out of the tank 10. A pair of cylindrically curved lead anodes 23 and 24 are mounted in the tank, in close proximity to the two lower quadrants of the cylindrical face of the cathode. Only narrow annular electrolyte spaces 25 and 26 are left between the anodes and the adjacent face of the cathode. The heavy anodes are supported in place by vertical support plates 27 mounted on brick through bus bars 29.

When a direct electric current is passed (at sufficient voltage) from the anodes 23, 24 through copper-bearing electrolyte in the electrolyte spaces 25, 26 to the cathode drum 16, copper is electrodeposited on the cylindrical face of the drum. As the drum rotates, this deposit is carried to above the surface of the electrolyte in the tank 10. There it is separated as a sheet 30 from the face of the drum by passing it over a stripping roll 31, and it is then wound into a coil 32 on a coil core 33. The coil core is mounted on a shaft 34 which is continuously driven by a sprocket chain 35 from the drive shaft 22, in order to maintain the copper sheet 30 under tension as it is stripped from the cathode.

In accordance with the invention, a discharge manifold 36 is mounted between the spaced adjacent lower edges of the anodes 23 and 24, where it extends parallel to the surface of the cathode drum adjacent the line of deepest immersion thereof. The discharge manifold is supported in place by means of a pair of end brackets 37 (only one of which is shown in Fig. 1) and one or more center brackets 38.

The construction of the discharge manifold 36 is Shown in detail and on an enlarged scale in Figs. 2 and 3. It

comprises lower and upper semi-cylindrical members 39 and 40 (formed, for example, by splitting a lead pipe longitudinally into two equal parts) joined together with a longitudinal partition 41 therebetween and closed at their ends. A solution distribution compartment 42 is 1 defined between the lower member.39 and the partition 41, and a solution discharge compartment 43 is defined between the upper member 40 and the partition 41. The discharge compartment is preferably divided into a plurality of sub-compartments 44 by a series of spaced transverse partitions 45. A solution inlet conduit 46 is provided for admitting electrolyte to the distribution comfrom the inlet conduit, thereby to insure substantially uniform distribution of solution to each of the discharge subcompartments 44. At least one and preferably two rows of closely spaced solution outlet openings 48 are formed j in the upper member 40 defining the solution discharge compartment. Thus, whensolution is delivered to the drum 16 of lead is supported by v discharge manifold through the inlet conduit 46, it is uniformly distributed through the distribution compartment to each discharge subcompartment and therefrom is projected through the discharge openings 48.

As indicated in Fig. l, the discharge manifold is mounted so that the streams of solution projected from the discharge openings 48 are delivered into the narrow electrolyte spaces 25 and 26 between the anodes and the cathode face of drum 16. The solution inlet conduit 46 is connected to a valved supply pipe 49 through which electrolyte solution under pressure is delivered to the apparatus.

In operation of the above-described apparatus, the tank 10 is filled with a suitable electrolyte, c. g. an acidic aqueous solution of copper sulfate. A source of direct current is connected to the cathode drum 16 and to the anodes 23 and 24. The drive shaft 22 is set in operation, whereby the durm 16 is slowly rotated (in a counterclockwise direction as viewed in Fig. l). The voltage between anodes and cathode is high enough so that copper is electrodeposited from the electrolyte in the spaces 25 and 26 between anodes and cathode on to the surface of the cathode drum. As the drum rotates, this electrodeposit is carried to above the surface of the electrolyte in the tank. conventionally, the deposit on the drum is carefully washed to remove residual electrolyte (by washing means not shown in the drawings). The electrodeposit then is stripped from the face of the drum in the form of the thin sheet 30 and is wound into the coil 32.

The face of the drum from which the copper sheet 30 has been stripped passes under a polishing roll 50 which is continuously rotated at relatively high peripheral speed by a drive chain 51 which connects it to a continuously driven high speed polisher drive shaft 52. The polishing roll 50 maintains a fine smooth surface on the cathode drum to insure the formation of a cathode deposit of good quality and to insure ease of stripping of the deposit from the cathode.

In accordance with the method of the invention, electrolyte solution is introduced continuously and under pressure from the supply pipe 49 through the inlet conduit 46 to the discharge manifold 36. This electrolyte, which enters the distribution compartment 42 and is distributed thereby to the several discharge sub-compartments 44, is forcibly projected as a series of high velocity streams through the discharge outlets 48 into the electrolyte spaces 25 and 26. The electrolyte of thesestreams, together with electrolyte present in the tank and which is set into circulation by the force of the streams, flows upwardly through the electrolyte spaces toward the surface of the electrolyte'at each side of the drum. Thus the electrolyte between the anodes and the cathode is continuously maintained in fast flowing turbulent motion and is continuously renewed and replenished.

The electrodeposited film of copper formed on the cathode drum surface while carrying out the method of this invention is of exceptional uniformity. Its gage thickness across the entire width of the drum issubject to but slight variation, and it is remarkably free of pinholes and other porosity even when stripped from the drum in sheets of extreme thinness (e. g. one ounce in weight per square foot of surface area, which in the case of copper corresponds to an average gage thickness of only a little over 0.001 inch).

I-Ieretofore it has been common practice to inject air into the electrolyte spaces 25 and 26 between the drum face and the-anodes, thereby to promote agitation of the electrolyte adjacent the face of the drum. When employing the method of the present invention, no such air injection is necessary, and in fact it is preferable that the streams 'of liquid electrolyte projected through the discharge outlets of the manifold 36 be free of any intentionally injected air or other gas. The resulting freedom of theelectrolyte from the effects of air agitation results in many improved operating conditions. In particular, the amount of acid electrolyte mist carried into the at mosphere is very greatly reduced, with the result that working conditions in the vicinity of the apparatus are greatly improved, the discoloring effect of such mist on the stripped electrodeposited sheet is eliminated, and the corrosive effect of the atmosphere on machine parts is greatly reduced. Also, the splashing and sloshing of electrolyte at its surface level in the tank is eliminated with a number of consequent advantages. Notable among these is the substantial elimination of splashing of the electrolyte on to the surface of the cathode, in the vicinity of the polishing roll 50, which invariably results in occasionally entrapping specks of lead dust generated by the polishing roll 50 and causes them to adhere to the surface of the cathode drum. These specks are then carried on the drum surface to beneath the surface of the electrolyte where they give rise to the defect of leaded porosity in the cathode deposit formed on the drum. The elimination of splashing of the electrolyte also greatly reduces the maintenance work required on account of corrosion of machine parts that are necessarily located close to the electrolyte surface.

It is thus apparent that the method and apparatus of this invention make it possible to produce electro deposited sheet metal of significantly improved quality, and at the same time to greatly improve the operating conditions and to reduce the maintenance work incident to such production.

I claim:

1. Apparatus for producing sheet metal by electrodeposition from an electrolyte solution, comprising a cathode drum mounted for rotation on a horizontal axis, a cylindrically curved anode mounted in closely spaced relation with the cathode drum, and means for projecting a flow of electrolyte into the space between anode and cathode comprising a discharge manifold extending along an edge of the anode, said discharge manifold comprising an elongated tubular member divided longitudinally into a distribution compartment and a discharge compartment communicating with said distribution compartment, means for delivering electrolyte solution into the distribution compartment of said discharge manifold, and said discharge compartment being provided with a series of spaced solution outlets along substantially the entire length of the discharge manifold, said outlets being so positioned as to project a stream of electrolyte delivered under pressure into said distribution compartment into the space between the anode and the cathode drum to cause the electrolyte to flow along the surface of the cathode drum opposite said anode.

2. Apparatus for producing sheet metal by electrodeposition from an electrolyte solution comprising a cathode drum mounted for rotation on a horizontal axis, a pair of cylindrically curved anodes each mounted in closely spaced relation with one of the lower quadrants of the cathode drum, the adjacent edges of said anodes being spaced apart substantially along the lowermost portion of the cathode drum, and means for projecting a flow of electrolyte into the space between anode and cathode comprising a discharge manifold positioned between the spaced adjacent edges of the anodes, said discharge manifold comprising an elongated tubular member divided longitudinally into a distribution compartment and a discharge compartment communicating with said distribution compartment, means for delivering electrolyte solution into the distribution compartment of said discharge manifold, and said discharge compartment being provided with a series of spaced solution outlets along substantially the entire length of the discharge manifold, said outlets being positioned so as to project a stream of electrolyte delivered under pressure into said distribution compartment into the space between the anode and the cathode drum to cause the electrolyte to flow along the surface of the cathode drum opposite said anode.

3. In apparatus for producing sheet metal by electrodeposition, a discharge manifold comprising an elongated tubular member divided longitudinally into a distribution compartment and a discharge compartment, said compartments being in communication with each other at intervals along the length of the manifold, means for delivering electrolyte solution under pressure into said distribution compartment, and said discharge compartment being formed with a row of closely spaced solution outlets along substantially the entire length of the discharge manifold, whereby a stream of electrolyte solution delivered into the distribution compartment is distributed thereby to the discharge compartment along the length thereof and is projected with substantially uniform force through each of said outlets.

4. In apparatus for producing sheet metal by electrodeposition, a discharge manifold comprising an elongated tubular member divided by a longitudinal partition into a distribution compartment and a discharge compartment, inlet means for introducing electrolyte solution under pressure into said distribution compartment, said partition being formed with a spaced series of openings providing communication between the distribution and discharge compartments, said openings being of progressively larger size as they become more remote from said inlet means, and said discharge compartment being formed with a row of closely spaced solution outlets along substantially the entire length of the discharge manifold, whereby a stream of electrolyte solution delivered into the distribution compartment is distributed thereby to the discharge compartment along the length thereof and is projected with substantially uniform force through each of said outlets.

5. In apparatus for producing sheet metal of electrodeposition, a discharge manifold comprising an elongated tubular member divided by a longitudinal partition into a distribution compartment and a discharge compartment, transverse partitions dividing said discharge compartment into a series of sub-compartments, inlet means for intro ducing electrolyte solution under pressure into said distribution compartment, said longitudinal partition being formed with a spaced series of openings, each such opening providing communication between one of the subcompartments of the discharge compartment and the distribution compartment, and such openings becoming progressively larger as they become more remote from said inlet means, and said discharge manifold being formed with a row of discharge openings extending along'substantially its entire length, said openings being arranged so that several are provided in each sub-compartment of the discharge compartment, whereby a stream of electro lyte solution delivered into the distribution compartment is distributed thereby substantially uniformly to each subcompartment and is projected with substantially uniform force through each of said discharge openings.

References Cited in the file of this patent UNITED STATES PATENTS 646,313 Rhodin Mar. 27, 1900 1,760,359 Hiss May 27, 1930 1,969,054 Wilkins- Aug. 7, 1934 1,991,678 Jephson Feb. 19, 1935 2,044,415 Yates June 16, 1936 2,256,729 Thompson Sept. 23, 1941 2,324,859 Macan July 20, 1943 2,328,162 Mercil Aug. 31, 1943 2,477,808 Jones Aug. 2, 1949 2,569,367 Bradner et al. Sept. 25, 1951 

1. APPARATUS FOR PRODUCING SHEET METAL BY ELECTRO DEPOSITION FROM AN ELECTROLYTE SOLUTION, COMPRISING A CATHODE DRUM MOUNTED FOR ROTATION ON A HORIZONTAL AXIS, A CYLINDRICAL CURVED ANODE MOUNTED IN CLOSELY SPACED RELATION WITH THE CATHODE DRUM, AND MEANS FOR PROJECTING A FLOW OF ELECTROLYTE INTO THE SPACE BETWEEN ANODE AND CATHODE COMPRISING A DISCHARGE MANIFOLD EXTENDING ALONG AN EDGE OF THE ANODE, SAID DISCHARGE MANIFOLD COMPRIING AN ELONGATED TUBULAR MEMBER DIVIDED LONGITUDINALLY INTO DISTRIBUTION COMPARTMENT AND A DISCHSRGE COMPARTMENT COMMINUCATING WITH SAID DISTRIBUTION COMPARTMENT, MEANS FOR DELIVERING ELECTROLYTE SOLUTION INTO THE DISTRIBUTION COMPARTMENT OF SAID DISCHARGE MANIFOLD, AND SAID DISCHARGE COMPARTMENT BEING PROVIDED WITH A SERIES OF SPACED SOLUTION OUTLETS ALONG SUBSTANTIALLY THE ENTIRE LENGTH OF THE DISCHARGE MANIFOLD, SAID OUTLETS BEING SO POSITIONED AS TO PROJECT A STREAM OF ELECTROLYTE DELIVERED UNDER PRESSURE INTO SAID DISTRIBUTION COMPARTMENT INTO THE SPACE BETWEEN THE ANODE AND THE CATHODE DRUM TO CAUSE THE ELECTROLYTE TO FLOW ALONG THE SURFACE OF THE CATHODE DRUM OPPOSITE SAID ANODE. 